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Pro-Ject Pre Box S2 digital DAC

Hello!
Please can someone advise me how to build a usb cable that does not bring power but is recognized by computer and Pro-ject S2 dac?
Thank you
Ercole
 
JohnW said:
Yes, its better to have the DAC connected to the PC via USB ONLY then using a switching PSU.

A Linear PSU is the very best solution (or Battery power)....
Click to expand...

I've been sharing your general comment that the manual is wrong for two months. I'll have to let people know you recommend only linear PSUs.

Some of us here have found that the included switching PSU improves the sound over USB. But — due to our incurable audiophilia affliction — we very quickly moved on to linear PSUs anyway.
 
Thank you for the link.
But something strange happens: I welded a usb cable with connected ground to pin 4, data to pins 2 and 3; using this cable my Cambridge Dacmagic is detected by the computer and works regularly, so also a assembled dac of Jlsound; instead only the Pro-ject is not detected.
What could be the problem?
Does anyone use a cable without positive voltage with the Pro-ject S2 DAC?
 
Ercole said:
Thank you for the link.
But something strange happens: I welded a usb cable with connected ground to pin 4, data to pins 2 and 3; using this cable my Cambridge Dacmagic is detected by the computer and works regularly, so also a assembled dac of Jlsound; instead only the Pro-ject is not detected.
What could be the problem?
Does anyone use a cable without positive voltage with the Pro-ject S2 DAC?
Click to expand...

Interesting. Thanks for doing this experiment. When connected via USB the Pro-Ject wakes and sleeps in sync with the computer. It's possible that the Pro-Ject needs to sense power on the USB line even if it then switches to the external power adapter. The automatic sleep feature is giving me occassional trouble with my ultraRendu too, although this seems a bit better since the last kernel update. I guess a USB data-only cable won't fix the ultraRendu problem either.
 
My Pre Box S2 has just arrived and so I have just started to play with it. I have it set up as a USB DAC/headphone amp on my PC which means that it is pretty much always on, and I was concerned about the OLED screen showing the same information for long periods. Is there any way to get the screen to dim (or even switch off) after a period of inactivity?
 
The Moog said:
My Pre Box S2 has just arrived and so I have just started to play with it. I have it set up as a USB DAC/headphone amp on my PC which means that it is pretty much always on, and I was concerned about the OLED screen showing the same information for long periods. Is there any way to get the screen to dim (or even switch off) after a period of inactivity?
Click to expand...

Part of the screen will go to sleep when the PC does, but if powered by the PC then the only way to completely turn it off is to shut down the PC. If on external power, then put the adapter on a power strip with a switch and turn it off while the PC is asleep or shut down.
 
I am currently running it just from USB power as advised by John for sound quality (and because it takes up one less plug socket!). I did try and use the adaptor thinking that I could turn it off manually when I wasn't at the PC, but then it just reverts to pulling power from the USB connection. Problem is that the PC is always on, so the only way to remove power from the Pre Box S2 is to pull out the USB cable, not ideal!
It would be great to include a screen dimming feature like on the MDAC, where the screen is set to full brightness when changing a setting, but can then dim after a set time to save on wear.
 
JohnW said:
Yes, its better to have the DAC connected to the PC via USB ONLY then using a switching PSU.

A Linear PSU is the very best solution (or Battery power)....
Click to expand...
That's not correct, at least not for me. The iFi iPower gives a very noticeable increase in sound quality when used for me, compared to USB power only.
 
MagnusH said:
That's not correct, at least not for me. The iFi iPower gives a very noticeable increase in sound quality when used for me, compared to USB power only.
Click to expand...

Would it be possible for a representative from Pro-Ject to clarify the situation here? USB and PSU? or USB only?
 
Last edited:
TreborF said:
Would it be possible for a representative from Pro-Ject to clarify the situation here? USB and PSU? or USB only?
Click to expand...

There is no official representative from Pro-Ject here. The lead developer, @JohnW who is not a Pro-Ject employee, has been posting here on his own time.

To summarize previous posts:

• The manual says we should use the included switching PSU for coaxial and optical input only, and when connected via USB we should not use the PSU.

• A few months ago @JohnW encouraged us to ignore that part of the manual and experiment with using external adapters with USB for better sound quality. When an external power adapter is connected, the device auto-switches from USB power to the adapter. All or most of us have found this improves the sound.

• At the end of December, John stated that we should do this only with a linear or battery PSU. See his posts at the top of this page and the end of the previous page for further explanation.
 
left channel said:
There is no official representative from Pro-Ject here. The lead developer, @JohnW who is not a Pro-Ject employee, has been posting here on his own time.

To summarize previous posts:

• The manual says we should use the included switching PSU for coaxial and optical input only, and when connected via USB we should not use the PSU.

• A few months ago @JohnW encouraged us to ignore that part of the manual and experiment with using external adapters with USB for better sound quality. When an external power adapter is connected, the device auto-switches from USB power to the adapter. All or most of us have found this improves the sound.

• At the end of December, John stated that we should do this only with a linear or battery PSU. See his posts at the top of this page and the end of the previous page for further explanation.
Click to expand...

Thanks for clearing things up.
 
left channel said:
There is no official representative from Pro-Ject here. The lead developer, @JohnW who is not a Pro-Ject employee, has been posting here on his own time.

To summarize previous posts:

• The manual says we should use the included switching PSU for coaxial and optical input only, and when connected via USB we should not use the PSU.

• A few months ago @JohnW encouraged us to ignore that part of the manual and experiment with using external adapters with USB for better sound quality. When an external power adapter is connected, the device auto-switches from USB power to the adapter. All or most of us have found this improves the sound.

• At the end of December, John stated that we should do this only with a linear or battery PSU. See his posts at the top of this page and the end of the previous page for further explanation.
Click to expand...

hi @left channel , thanks for summarising. Either on this forum or some other JohnW did add that SMPS supplies are bad primarily cause they could/can/do create leakage currents (in addition to spitting noise back into power lines but maybe that can be addressed with filters).
Some audiophiles love uptone audios LPS-1 power supply which is battery-like and has no issue of leakage currents. It's designer did post findings on how to accomplish (some of that) with regular SMPS power supplies: https://www.computeraudiophile.com/forums/topic/37034-smps-and-grounding/
Such a simple tweak (connect ground from your power outlet with negative/ground output from your power supply) ... should address key concerns of SMPS's ... both the one that Pro-Ject supplies as well as 'better' - like iFi Power Supply. That is what I have just done - costs 2-3 $ ... i spent 7 or 8 and got set of 10 adapters that I am going to use to reduce leakage currents on (any) SMPS power supply.

Since measurements by @John Swenson show dramatic reduction of said currents, and iFi power output is really clean from noise - it should create (for 2$ and/or 50$ for iFi) - almost optimal situation for very few $.

I doubt i am hearing any differences ... but for those with golden ears - will take few bucks and 5minutes to set it up :)

my 2 cents
 
so if I were to use this as a stand alone DAC, is there any way to bypass the volume control?
I'm assuming the RCA's are variable output
 
Just set the Volume level to 0dB on the DAC - then there is no attenuation as the attenuation is performed in the digital domain (which is now set to 0).
 
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